1. Field of the Invention
The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device which includes a backlight.
2. Description of the Related Art
A liquid crystal display panel is configured such that an envelope is formed of a pair of substrates which sandwiches liquid crystal therebetween, and optical transmissivity of the liquid crystal display panel is controlled over a plurality of pixels which are formed in the spreading direction of the liquid crystal. Accordingly, a liquid crystal display device is usually provided with a backlight which is a planar light source on a surface (back surface) of the liquid crystal display panel on a side opposite to a viewer.
Such a liquid crystal display device is configured to radiate light from the backlight through the liquid crystal display panel with a relatively large angle with respect to a perpendicular of the liquid crystal display panel. That is, the liquid crystal display device is a liquid crystal display device having a so-called wide viewing angle characteristic which allows a plurality of viewers to observe an image on the liquid crystal display panel simultaneously.
On the other hand, however, there has been also a demand that, for example, only a viewer himself is allowed to observe an image on the liquid crystal display panel. For example, as disclosed in JP-A-1994-59287, there has been known a liquid crystal display device which can adjust a viewing angle state from a wide viewing angle state to a narrow viewing angle state.
The liquid crystal display device disclosed in JP-A-1994-59287 is configured such that a guest-host liquid crystal cell is arranged between a backlight and a liquid crystal display panel and hence, when the guest-host liquid crystal cell is driven, light from the backlight can be radiated with a small angle with respect to a perpendicular of the liquid crystal display panel. The guest-host cell per se can adjust a viewing angle of light which passes through the guest-host liquid cell.